An article entitled "Shuttle Orbiter Flash Evaporator" by J. R. Nason et al. and published by the American Society of Mechanical Engineers in 1979 describes a flash evaporator in which the cooling liquid that needs to be cooled, circulates through a gap between two housing walls enclosing an evaporation chamber into which an evaporation fluid is introduced, for example, by spraying. Thus, the cooling liquid that needs to be cooled down is in thermal contact with the evaporation fluid that is being evaporated in the evaporation chamber. The housing is preferably a cylindrical container and the walls forming the housing are constructed as so-called cores which are grooved in the axial direction as shown in FIG. 2 of the above mentioned article. The cooling liquid that needs to be cooled, flows through the ring gap which has a corrugated cross-sectional configuration as shown in FIG. 2 of the article. The cooling liquid that needs to be cooled and which circulates in one or several active cooling circuits, is brought into thermal contact with the evaporation fluid by passing the cooling liquid to be cooled through the corrugated housing walls. The evaporation fluid is injected through one or more injection nozzles to form a jet of evaporation fluid droplets inside of the evaporation chamber of the heat exchanger. The droplets contact the inner surfaces of the housing walls forming the evaporation chamber, whereby the droplets take up heat from the liquid to be cooled and evaporate. The resulting vapor or steam is removed through a discharge opening in the evaporator housing and discharged into the environment of the spacecraft.
Using a device of the type described above under operating conditions free of gravity, and under different acceleration conditions during the starting and landing of the spacecraft, poses a basic problem of how to bring the evaporation fluid and the liquid to be cooled that flows through its cooling circuit, into an efficient heat exchange contact with each other. It is important to use the evaporation fluid as efficiently as possible to convert it substantially completely into the vapor phase, because the evaporation fluid must be carried by the spacecraft at the expense of other payloads. In order to improve the heat transfer between the cooling liquid that needs to be cooled on the one hand and the evaporation fluid on the other hand, the flash evaporator described by Nason et al. uses the above mentioned grooves in the gap between the two coaxially arranged cylindrical housing walls. The grooves are made of corrugated sheet metal formed into a cylinder member held between the cylinder walls forming the housing by brazing the corrugated cylinder member to the housing walls.